BILLINGS, Mont. (AP) - Montana Republicans resolved Saturday to close their primary elections to nonparty members and adopt a runoff system for the general election, following a fierce internal debate that underscores lingering divisions within the party heading into the general election season.

The proposals were adopted by a voice vote taken of roughly 200 delegates at the party’s election-year convention in Billings.

The changes will not go into effect automatically. They would have to be approved by the state Legislature or imposed by the courts after a successful federal lawsuit.

Support for closed primary elections was strongest among conservatives, who complained bitterly about outside interference during the June 3 primary. There were indications in some legislative races that Democrats crossed over during the primary to support moderate Republicans, the conservatives claimed.

State Sen. Jeff Essmann of Billings, who introduced the proposal, said it was an issue of fairness.

“It’s about the election of Democrats by Democrats, Libertarians by Libertarians and Republicans by Republicans,” Essmann said.

Opponents of the idea said it would give conservatives a lock on the party at the expense of alienating voters who are needed to win general elections.

“We’ve had an election and there were some results people didn’t like. Instead of looking back at what happened during the campaign, now they want to change the rules,” Fitzpatrick said. “The simple fact of the matter is we need to do a better job running races.”

Others opposed to closed primaries said they already had heard from constituents threatening to quit the party if they were forced to declare their affiliation in order to vote.

Twenty-four states have closed Republican primaries, and 19 states have closed Democratic primaries, according to the nonpartisan Maryland-based group FairVote.

Republicans on both sides of the issue sought to downplay the divisions over the primary that emerged during the convention.

Essmann, who is leaving the Senate because of term limits and seeking a House seat, said the issue amounted to “inside baseball” that voters won’t take much interest in it. Closed primary opponent Rep. Mike Miller of Helmville agreed that other issues would take precedence in November.

A second resolution added to the party’s platform on Saturday said that candidates should be required to get a majority of votes cast in order to win a general election. For example, if no candidate had a majority in a three-way race, the top two vote-getters would advance to a runoff.

Supporters said such a change could help prevent a third-party candidate from hurting a Republican’s chances by peeling off voters who would otherwise side with the GOP.

Delegates narrowly defeated a proposal to hold party endorsement conventions in advance of the primary. Under the proposal, party leaders would formally endorse candidates for statewide office and the public service commission at least 50 days before the primary.

Supporters said the early endorsements would stir support by drawing more people to conventions and bolstering the chances of the chosen candidates during the general election.

But a parade of critics said the idea would alienate voters and allow top-ranking party members to control who gets into office.

Sen. Bruce Tutvedt of Kalispell said the endorsements would lead to infighting among different factions of the party.

“If we further pick our candidates instead of allowing the voters to do it, we’re going to have a mess,” Tutvedt said.